In the conventional manufacture of the portable computer, the mechanism design is mainly based on the electronic unit layout that defined by the predetermined formats in order to connect the related connecting line and module design to the motherboard, such as hard disk drive, optical disk drive, keyboard, and touch panel etc. Also, the motherboard is screwed on the base of the casing in traditional assembling process. Besides, the conventional motherboard has been installed in the casing first, and then the corresponding connecting lines and modules are assembled. Thus, if the motherboard is under the condition of replacement or maintenance, the entire casing must be dismantled before the removal of the motherboard. As a result, the maintenance becomes quite complicated and difficult, and the cost and time of maintenance are increasing accordingly. Moreover, the connecting lines used thereof are vulnerable for frequently plugging in and unplugging. Furthermore, if the user wants to take the entire casing apart, the portable computer might be easily damaged and the guarantee issue might be raised.
Besides, the input/output port (I/O port) is integrated into the exterior design of the portable computer. That is, the I/O port layout of the motherboard must is consistent with the appearance of the casing. Therefore, the motherboard in accordance with the casing must be designed separately, which increases the stocking and management cost.